1. Field of the Invention
The present invention, generally relates to a manufacturing method of a semiconductor device and a semiconductor device and, more particularly, to a manufacturing method of a semiconductor device and a semiconductor device which device has a redistribution layer.
Recently, as a semiconductor device has been rapidly miniaturized and given a higher density, mounting terminals thereof have accordingly been narrowly pitched. Especially for a CSP (Chip Size Package), the above-mentioned narrow pitch makes a serious problem when the CSP has mounting terminals provided on electrode pads formed on the periphery of a semiconductor element, because the semiconductor element has substantially the same size as the package itself.
Due to this, mounting terminals and electrode pads are formed in an offset state so that the mounting terminals are formed in a matrix in a package. This structure requires wirings (hereinafter referred to as redistribution layers) to connect the mounting terminals and the electrode pads.
On the other hand, a semiconductor device is required to be manufactured at a low cost. Accordingly, the above-mentioned redistribution layers need to be formed at a low cost.
2. Description of the Related Art
Recently, wafer-level techniques have been applied in manufacturing a CSP-type semiconductor device, in which techniques redistribution layers are formed before dicing (separating into pieces) a wafer.
In a conventional method of forming a redistribution layer on a wafer, a resist is first formed on a wafer except on an electrode pad and a region on which the redistribution layer is to be formed. Then, a metal film is formed as a redistribution layer by sputtering or electroplating. In this process, copper (Cu) is used as a material of the redistribution layer because of good electric conduction. Additionally, a surface plating of nickel (Ni) or gold (Au) is provided on the metal film, if necessary.
After the metal film is formed, the resist is removed so as to complete forming the redistribution layer that is electrically connected to the electrode pad on the wafer. After the redistribution layer is formed, steps including a step of forming a sealing resin and a step of providing a mounting terminal are performed. Thereafter, the wafer is diced into each semiconductor device.
As described above, a conventional method of manufacturing a semiconductor device employs a sputtering method or an electroplating method to form a redistribution layer. However, using a sputtering method requires expensive manufacturing facilities so as to raise a product cost of the semiconductor device.
In using an electroplating method, a base metal film needs to be preparatorily formed as an electrode connected to a power source at a position at which the redistribution layer is to be formed, which complicates the manufacturing steps. Further, in using the electroplating method, since a metal film is deposited slowly., forming a thick redistribution layer requires a long time so as to reduce a manufacturing efficiency thereof.